1. Field of the Invention
The present invention relates to a system providing bidirectional communication services, and more particularly, to a user request processing method and apparatus using an upstream channel in interactive multimedia contents services.
2. Description of the Related Art
In order to provide various functions for interactive multimedia contents services, in the field for providing bidirectional communication services, for example, in the field of moving picture expert group (MPEG)-4 system (ISO/IEC JTC 1/SC 29/WG11 14496-1), various technologies for enabling those services are being standardized. To satisfy various requirements from users who receive multimedia contents services, those systems are providing functions for each multimedia contents provider processing various events occurring at user's sites, through an upstream channel of each multimedia contents provider.
Between a server (including an encoder) for encoding and managing data on arbitrary object information, and a user terminal (including a decoder) for receiving and restoring the data, two types of channels for transmitting data exist including a downstream channel for transmitting data from the server to the user terminal and an upstream channel for transmitting data from the user terminal to the server. When user's various requests should be processed frequently as in video-on-demand (VOD) or World Wide Web (WWW) environment, an upstream channel are used. That is, the upstream channel is used in a system for providing bidirectional communication services, in which necessary information is immediately provided from a server for services that cannot be processed in a user terminal.
For data, in which errors occurred, on an application which provides only one-way telecommunications services, the processing method from the system side is different from that from the user side. On the system side, the size of a transmission data packet on a channel is checked, or whether or not data error occurred is checked according to the data format types such as a parity bit, in a lower layer of a network, such as a TCP/IP layer. If an error occurred, the server receives the data again for processing the error. However, in this method, it is a problem that logical errors occurred in transmission data or retransmission service in order of importance of data to be restored cannot be provided from the system side. Therefore, to consider this problem, a system for providing bidirectional communication service is needed, in which the user terminal checks errors in the restoration process, and if an error exists, transmits related information for restoring original data to the server through an upstream channel, and then the server restores error-containing data, retransmits the data to the user terminal so that the original data can be restored and errors can be processed.
Meanwhile, an MPEG-4 system providing bidirectional communication services enables the use of an upstream channel provided by each multimedia content provider in processing various events occurring in a user terminal. However, more specifically, for example, in various interactive multimedia contents services such as providing three-dimensional scenes for users, and receiving a request of processing some nodes in a scene from a user, the MPEG-4 system does not propose how to process the user request using the upstream channel.